PC Basics: Checking or Assigning an IP Address

Just as every house on your street has a unique street address, each computer on a network must have a unique IP (Internet Protocol) address. Two houses with the same address would lead to confusion. Ditto for your network.

Checking your IP address

The IP address can be manually entered (by you) or automatically assigned by a single computer on the network or a router. To check the IP address, follow these steps:

1. Open the Network Connections window.

2. Double-click to open your Network Connections icon.

The connection's Status dialog box appears. The General tab tells you some information about the connection. Primarily, you can determine that the network is up and good because it says Status: Connected and the Activity area indicates information both sent and received.

3. Click the Support tab.

On the Support tab, you find the IP Address listed. It's one of those dotted numbers, like 10.0.1.1 or something similar. You also find two other important values listed:

• The subnet mask, which helps Ethernet find local computers on the network.

• The default gateway, which is required when your LAN is also connected to the Internet. The gateway is usually the IP address of the router.

4. Click the Close button.

IP addresses that start with 192.168 or 10.0 are used for the local network only. Other IP addresses are used on the Internet and can be assigned only by an ISP (Internet service provider) or some outfit with the authority to assign those numbers. Otherwise, the IP address you see with starts out with 192.168 or 10.0.

Manually assigning an IP address

In most situations, the IP address is assigned for you automatically, or dynamically. This happens when you use a router to connect your network and the router has been configured to deal out IP addresses. It also happens when you use Internet connection sharing. It may also happen if you just have one computer connected to a broadband modem. When it doesn't happen dynamically, you must manually assign an IP address to each computer in the network.

To manually assign an IP address, you use the network connection's Properties dialog box. Here's the nitty and the gritty:

1. Open the Network Connections window.

2. Right-click your networking icon and choose the Properties command from the pop-up menu.

3. On the General tab, click the item labeled Internet Protocol (TCP/IP).

4. Click the Properties button.

The TCP/IP Properties dialog box appears,

If you have a network computer that hands out IP addresses or you're using Internet connection sharing or you have a router that assigns IP addresses or you have a computer running the DHCP program, you can choose the option labeled Obtain an IP Address Automatically; skip to Step 8.

5. Type an IP address for the computer. Type 10, press Tab, type 0, press Tab, type 0, press Tab, and then type a number.

Each PC on your network must have a unique IP address.

6. Enter 255.0.0.0 as the Subnet mask.

7. Leave everything else alone.

8. Click OK and close any other open dialog boxes or windows.

The most important part of these steps is to ensure that no two PCs on the network use the same IP address. If they do, the network doesn't work. The IP addresses must be unique!